Carl Sandburg captures well how language is as fluid as a river. Rivers can shrivel up over time, and so can language. Poetry keep the languages of times, people, ideas, and civilizations from drying up.
Carl Sandburg (1878 – 1967)
There are no handles upon a language Whereby men take hold of it And mark it with signs for its remembrance. It is a river, this language, Once in a thousand years Breaking a new course Changing its way to the ocean. It is mountain effluvia Moving to valleys And from nation to nation Crossing borders and mixing. Languages die like rivers. Words wrapped round your tongue today And broken to shape of thought Between your teeth and lips speaking Now and today Shall be faded hieroglyphics Ten thousand years from now. Sing—and singing—remember Your song dies and changes And is not here to-morrow Any more than the wind Blowing ten thousand years ago.